In recent vehicles, electronic devices small in size and high in heat generation, such as a navigation apparatus, have been used. Cooling of heat generation units of those electronic devices is becoming increasingly important.
Up to now, a heat radiation component and a manufacturing method for the heat radiation component disclosed in Patent Document 1 have been known. In the disclosed technique, in order to reduce a thermal resistance between a circuit board and a heat sink which radiate a heat, beard-shaped carbon nanotubes (also referred to as “CNT”) or carbon fibers are embedded in a metal layer coming in close contact with the heat sink.
Non-Patent Document 1 discloses a technique in which carbon nanotubes are added into a composite of carbon fibers and aluminum, and sintered in plasma, thereby producing an object having a thermal conductivity of three times or more as high as aluminum.
Further, in Non-Patent Document 1, attention is paid to vapor grown carbon fibers (VGCF or simply referred to as the carbon fibers) that exist apart from the other vapor grown carbon fibers without any contacts and do not contribute to heat transfer inside of a composite material of the vapor grown carbon fibers and aluminum. The subject vapor grown carbon fibers and the other vapor grown carbon fibers are crosslinked with carbon nanotubes small in size to improve a thermal conductive characteristic.
In the configuration disclosed in Patent Document 1, the circuit board and the heat sink are adjacent to each other and integrated together, and there is a limit to the mountability and the assembly of those components in a vehicle. Therefore, such a configuration may not be preferable for cooling of the electronic devices dispersed inside of the vehicle. In other words, even if heat generated in semiconductor can be efficiently transferred to the heat sink, the electronic devices have to be cooled by air cooling of the heat sink, individually, and there is a limit to the cooling of the semiconductor associated with a cooling performance of the heat sink.
When the heat sink is upsized, a blower is upsized, or a refrigerant in a refrigeration cycle is introduced, the configuration is increased in size and complicated. As a result, the mountability and the assembly of those components in the vehicle may be lowered. Furthermore, it is conceivable to use a well-known heat pipe as the heat transfer member, but flexibility lacks to struggle against assembly.
In addition, in the technique of Non Patent Document 1, although the thermal conductive characteristic of the composite material of the vapor grown carbon fibers, the carbon nanotubes, and aluminum is improved, there is no disclosure of an improvement in the mountability and the assembling in the vehicle.